Journey of micronanoplastics with blood components

The entry of micro- and nanoplastics (MNPs) into the human body is inevitable. They enter blood circulation through ingestion, inhalation, and dermal contact by crossing the gut–lung–skin barrier (the epithelium of the digestive tract, the respiratory tract, and the cutaneous layer). There are many reports on their toxicities to organs and tissues. This paper presents the first thorough assessment of MNP-driven bloodstream toxicity and the mechanism of toxicity from the viewpoint of both MNP and environmental co-pollutant complexes. Toxic impacts include plasma protein denaturation, hemolysis, reduced immunity, thrombosis, blood coagulation, and vascular endothelial damage, among others, which can lead to life-threatening diseases. Protein corona formation, oxidative stress, cytokine alterations, inflammation, and cyto- and genotoxicity are the key mechanisms involved in toxicity. MNPs change the secondary structure of plasma proteins, thereby preventing their transport functions (for nutrients, drugs, oxygen, etc.). MNPs inhibit erythropoiesis by influencing hematopoietic stem cell proliferation and differentiation. They cause red blood cell and platelet aggregation, as well as increased adherence to endothelial cells, which can lead to thrombosis and cardiovascular disease. White blood cells and immune cells phagocytose MNPs, provoking inflammation. However, research gaps still exist, including gaps regarding the combined toxicity of MNPs and co-pollutants, toxicological studies in human models, advanced methodologies for toxicity analysis, bioaccumulation studies, inflammation and immunological responses, dose–response relationships of MNPs, and the effect of different physiochemical characteristics of MNPs. Furthermore, most studies have analyzed toxicity using prepared MNPs; hence, studies must be undertaken using true-to-life MNPs to determine the real-world scenario. Additionally, nanoplastics may further degrade into monomers, whose toxic effects have not yet been explored. The research gaps highlighted in this review will inspire future studies on the toxicity of MNPs in the vascular/circulatory systems utilizing in vivo models to enable more reliable health risk assessment.

Er R. Durgalakshmi is currently a Research Scholar in the Centre for Nanobiotechnology at Vellore Institute of Technology, Vellore, Tamil Nadu, India -632014.Her research focuses on the toxicity of micro/ nanoplastics (MNPs) and how they interact with human biomacromolecules.She is particularly focused on investigating the adsorptive behavior of MNPs and how they affect the human circulatory system, mainly human blood proteins, through in-depth analysis incorporating spectroscopic techniques.Other areas of research include microbiology, bioproducts, nanoparticle synthesis, and their applications.She has published 12 research papers and one book chapter during her research career.

Natarajan Chandrasekaran
Professor Natarajan Chandrasekaran, formerly Director, Centre for Nanobiotechnology, Vellore Institute of Technology (VIT), has made several conceptually important and widely cited contributions to the area of toxicology and environmental sciences.He has published 382 peer reviewed publications with an h-index of 68, total citations: 17,671, i10-index 261.He has made pioneering contributions in the preparation and applications of neem-nanoemulsion biopolymer beads for controlling bacterial infection in hatchery animals, neem-nanoemulsion-laced urea biopolymer beads for the control of Japanese encephalitis vectors in rice elds, nanopermethrin for mosquito repellency, and exopolysaccharide-loaded nanoemulsion cross-linked biopolymer nanocomposites as a wound healing gauze.

Introduction
Plastic is a ubiquitous material in our daily lives that has become unavoidable.Due to its exceptional physical and chemical properties-including exibility, infrangibility, low density, low electrical conductivity, etc.-as well as its low cost, plastic has essentially supplanted the usage of wood and metal in many applications. 1The most common types of plastics used globally in medical, industrial, and consumer products are polypropylene (PP; medical and electronic equipment, straws, furniture), 2 polyethylene (PE), which is mainly used in its lowdensity form (LDPE; bin bags, plastic wrap, shopping bags) and high-density form (HDPE; irrigation and drainage pipes, shampoo bottles, detergent bottles), 3 polyvinyl chloride (PVC; electrical cable insulation, doorframes, toys, pipes), 4 polystyrene (PS; foam food containers, plastic containers, rigid trays, audio and video cassettes, lids, and tumblers) 5 and polyethylene terephthalate (PET; bottles, vehicle tires, conveyers, drive or seat belts, food trays). 6,7Plastic is benecial; however, it takes hundreds of years to decompose and is not biodegradable.The natural environment is gradually becoming contaminated with plastic debris, including used plastic bags, bottles, and containers; this contamination has emerged as a critical global issue causing environmental stress and uncontrollable harm to living systems. 8 prognosis for 2050 predicts that the amount of plastic garbage in landlls and/or the environment will reach close to 12 000 Mt globally, and in seas and oceans, it will surpass sh. 9 Plastic fragments degrade when exposed to ultraviolet light, weathering, and biodegradation, resulting in the formation of a heterogeneous mixture of microplastics (MPs) and nanoplastics (NPs).These plastic residues are classied as large microplastics (5 mm to 1 mm), small microplastics (1 mm to 1 mm), and nanoplastics (<1 mm). 10 The ocean and other bodies of water are signicantly contaminated by these microplastics.Thompson et al. formally coined the term "microplastic" (MP) in 2004, in response to the growing problem of plastic pollution in the seas, and stated that these lightweight fragments follow atmospheric currents and are dispersed globally. 11Microplastics are therefore present in every environmental compartment (air, soil, and bodies of water) and their presence is increasing at an alarming rate.MPs can be classied into two groups: primary and secondary.Primary MPs are directly released into the environment as microscale plastics (<5000 mm), such as in cosmetic products, toothpaste, pharmaceutical vectors (nanovehicles), etc., The degradation of these primary MPs by mechanical or natural processes, i.e., weathering, UV radiation, or other atmospheric currents, leads to the synthesis of secondary MPs 12 Due to their smaller size, high mechanical strength, huge surface area, and high chemical activity, MPs and NPs have different physical and chemical properties compared to the bulk materials.Plastics oen have a surface charge as a result of the functionalization of plastic products during production to obtain the desired material properties.Common surface modications include amino groups (NH 2 ) to give positively charged surfaces, carboxyl groups (COOH) to give negatively charged surfaces, and non-functionalized raw plastic surfaces without any surface modication at all. 13,14A single plastic particle may have multiple distinct surface chemistries as a result of the environmental degradation process itself.6][17] This will affect their environmental fate and behavior, as well as their interactions with biological systems. 18MNPs, whether manufactured or resulting from environmental degradation or leaching from medical devices and utilities, can enter living beings through ingestion, inhalation, or dermal pathways.0][21][22] The ingestion of these particles has thus raised concerns about their potential impact on human health.
MNPs and pollutant complexes are ubiquitous and can enter the human body via inhalation, [23][24][25] ingestion, [26][27][28] or skin contact. 29Due to their smaller size, they are able to cross the gut-lung-skin barrier, [30][31][32] which refers to the epithelial lining of the intestine, lung, and cutaneous layer. 33By crossing this barrier, they enter the bloodstream and are distributed to other organs.6][47][48] However, the distributor of these particles to other organs is the blood and blood components. 41,49,50Hence, it is essential to analyze their interactions with blood components, as blood components are essential for many physiological activities and play an important part in preserving human health.They have major roles in the transportation of oxygen, nutrients, hormones, waste, external agents, etc. (plasma proteins and red blood cells (RBCs)), 51,52 defense (white blood cells, WBCs), 53 hemostasis (platelets), 54,55 control of temperature and pH, and uid management 52 in the body.Their harmful impacts on blood components can lead to several abnormalities, such as hemolytic diseases, 51 clotting and cardiovascular diseases, 56 and downregulated immune response. 53Research gaps exist regarding the fate and detrimental impact of MNPs in the bloodstream due to a lack of epidemiological statistics and practical toxicological approaches, as well as technological limitations for assessing MNPs.8][59][60] This indepth review article surveys the existing literature on the representative toxic impacts of MNPs on blood components, which will act as an eye-opener to other researchers to enable the lling of research gaps regarding toxicological data for MNPs in the vascular/circulatory system.

Methodology
The purpose of this review is to collect literature with a highlevel scope to identify relevant studies on the effect of nanoplastics and microplastics on blood and blood components and consolidate it into a comprehensive overview of the existing literature in this area.The PubMed, Google Scholar, Web of Science, ScienceDirect, and Scopus databases were searched for potential papers using search terms such as microplastic, nanoplastic, co-pollutants, environmental effects, human exposure, blood, blood components, and organ toxicity.Peerreviewed journal articles, books, reports, conference abstracts, and papers from the whole database record were included in this critical evaluation; consequently, no time frame was spec-ied.Additionally, publications in languages other than English, unpublished literature, and sources from predatory or suspicious journals were not taken into account for this review.To prepare this article, data from the search results were processed, divided into categories, and presented under relevant headings.The soware program Mendeley was used to cite the references.

Plastic pollution
MNPs are massive environmental pollutants to which humans and other environmental organisms are exposed over an extended period of time-almost their entire existence.Singleuse plastic bags are the main source of plastic pollution, since they ultimately wind up in landlls, oceans, and other waterways, endangering our ecosystem. 61Plastic pellets, cosmetics with microbeads, paint, baby toys, food and beverage containers, sewage sludge, and tires are some of the primary sources of environmental MNPs.Municipal wastes, such as plastic bags, water bottles, shing nets, and agricultural lm are secondary sources of MNPs. 62These plastics are degraded in the environment by means of biodegradation (mediated by environmental microorganisms) and non-biodegradation processes (thermal (high temperature), physical (weathering), photodegradation (UV from sunlight), and hydrolysis), eventually becoming MPs and NPs. 63Additionally, MPs and NPs are employed in bioimaging, 64 personal care products, 65 and medicine delivery. 66The lack of handling limitations results in higher occupational exposure during the production of primary MNPs, and improper disposal of their waste pollutes the environment. 13Depending on the degree of degradation, MNPs follow biogeochemical cycles involving the atmosphere, lithosphere (terrestrial), and hydrosphere (aquatic system), all of which are interconnected. 672][73] Sewage sludge utilized as fertilizer is the main source of plastic pollution in agricultural lands, as evidenced by sludge analysis in China (5553-13 460 particles of MNPs per kg of sludge). 74MNPs from the terrestrial environment reach the aquatic environment by natural erosion, surface runoff, 75 or escape from wastewater treatment plants. 76MNP debris has been found in abundance in aquatic environments in the United States (30.8 ± 12.1 particles per L), 77 Siberian Seas (0-0.045particles per m 2 ), 78 India (2-178 particles per m 2 ), North Atlantic subtropical gyre (13-501 particles per m 2 ), 79,80 China (20-340 particles per kg), 81 Sweden (0.18-0.92 particles per m 2 ), 82 and Canada (0.19 particles per m 2 ). 83In terms of atmospheric air currents, studies have reported the presence of airborne microplastics in Indonesia (132.75-174.97particles per m 3 ), 84 China (4.18 particles per m 3 ), 85 Iran (0.3-1.1 particles per m 3 ) 86 and many other countries.These widespread MNPs acquire different physiochemical characteristics, such as heterogenous size, shape, surface roughness, hydrophobicity, and surface functionalization, through geochemical cycles and weathering, as well as by absorbing co-existing contaminants. 87hese complex MNPs are then ingested by smaller organisms and make their entry into the food chain. 28,88

Co-existence of contaminants
MNPs have evolved into excellent vehicles for the transport of heavy metals, 89 persistent organic pollutants (POPs), 90 microbial pathogens, 91 and metabolized or unmetabolized pharmaceuticals [92][93][94] from an aquatic environment to other ecosystems.These environmental contaminants are produced through consumerism and commercialism. 95Heavy metals and hydrocarbon chemicals are released into the environment from mining and mineral processing. 16,96,97Farming methods are the root cause of the environmental presence of harmful pesticides, nitrates, phosphates, and mineral salts. 22,98Recent studies of wastewater treatment plant (WWTP) effluent and surface water have found extremely high quantities of pharmaceutical pollutants. 99,100However, all of these organic and inorganic compounds, including pesticides, heavy metals, hydrocarbons, minerals, and pharmaceuticals, are discharged into the environment from manufacturing industries through wastewater effluents.Domestic usage of all the above-mentioned chemicals is another major cause of their presence in garbage and sewage. 95MNPs are more likely to act as vectors of concurrent pollutants and pose a major threat to the environment due to their small size, high surface-to-volume ratio, and high reactivity.Other important physiochemical properties, such as their non-polar nature (polyethylene (PE), polypropylene (PP), polystyrene (PS) 101 ), amorphous structure (polyvinyl chloride (PVC), PS), and glass transition temperature of ∼90 °C (PVC, PS), 17 enable them to adsorb co-pollutants by forming chemical interfaces, such as van der Waals bonds, hydrophobic interactions, or intraparticle diffusion. 17As a result, unanticipated environmental risks may appear due to the "Trojan Horse" effect.For example, PE and PS adsorb sulfamethoxazole, 102 PP and PS adsorb tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes, 103 and PP, PE, PS, and PVC adsorb tylosin. 104PVC 105 and PE 106 have the capacity to adsorb the hydrophilic drug ciprooxacin.Among the plastics, polystyrene nanoplastics (PSNPs) adsorb a wide range of environmental contaminants such as pharmaceuticals (oxytetracycline, 107 ciprooxacin 105 ), POPs (polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and dichlorodiphenyltrichloroethane (DDT) 108 ), pesticides (pronil, 109 triadimenol (TRI), myclobutanil (MYC) and hexaconazole (HEX) 98 ), heavy metals (arsenic 110 ) and personal care products. 111PS adsorbs the heavy metal arsenic through hydrogen bonds, hydroxyl production, and surface adhesion, and transports it to the next habitat. 110Several kinetic studies on the interactions between microplastics and medicinal products have been primarily concerned with environmental issues.[114][115]

Potential impact of MNPs and copollutants on ecosystems
The negative impacts of accumulated MNPs on soil systems are unpredictable.Through a variety of toxic mechanisms, including bioaccumulation, oxidative stress, inammation, metabolic disorders, gut microbiota dysbiosis, genotoxicity, neurotoxicity, and reproductive toxicity, MNPs signicantly harm soil fauna, mostly earthworms and nematodes. 116This will have a negative effect on ecological processes such as nutrient cycling, energy ow, and litter decomposition, and poses numerous risks to the environment. 117Additionally, MNPs interact with other pollutants such as pesticides and other organic pollutants throughout their existence, increasing their potential for harm and severely damaging the terrestrial biota. 118The physiochemical characteristics of soil are affected by these complexes, leading to groundwater contamination, which inhibits plant growth and lowers overall productivity. 119dditionally, it has been noted that MNPs suppress the proliferation of microorganisms, including certain yeast, bacteria, and algae, which affects their crucial roles in various habitats. 120Numerous studies have been conducted on the health effects of MNPs on freshwater and marine organisms.In marine benthic animals (bivalves), such as mussels and oysters, MNPs have been observed to obstruct the digestive tract, which frequently results in decreased appetite, malnutrition, and fatalities. 121,122Bivalves are lter feeders 123 and mistakenly consume plastic particles as food; these particles are absorbed into their circulatory system and distributed throughout the body, affecting growth and reproduction. 124umerous studies on various marine creatures, including lugworms 125 and oyster larvae, 126 have revealed variable effects of plastic particles on growth and reproduction.In freshwater settings, studies have examined how MNPs affect zebrash and Daphnia magna.MNPs can be consumed by Daphnia magna and alter their feeding and excretion rate. 127MNPs have been found to accumulate in the tissues of zebrash and cause organ toxicity, inammation, lipid accumulation, oxidative stress, and metabolic effects. 128Another study reported that 21 day exposure to 10 000 particles per L of realistic MNPs increased oviposition and secondary patellar aneurysms in Japanese medaka. 129n addition to the direct toxicity of nanoplastics, it is important to take into account the possible toxicity of MNPs and coronated pollutants.Several combined toxicity studies of nanoplastics and co-pollutants have been conducted using aquatic organisms, [130][131][132][133][134] mouse models, 37,135 and cell lines. 136,137xidative stress brought on by exposure to pollutants can result in the generation of reactive oxygen species (ROS) and impairment of the antioxidant defense mechanisms in organisms. 138ecent studies have also revealed that when Scenedesmus obliquus and zebrash (Danio rerio) were exposed to both PSNPs and naturally occurring acidic organic polymers (NAOP), such as fulvic acid and humic acid, growth inhibition of the algae and oxidative stress in the zebrash were observed. 139Ibuprofen showed synergistic toxicity with PSNPs through suppressing growth in Chlorella pyrenoidosa, indicating pharmaceuticalassisted toxicity. 134Antibiotics-doxycycline, in particularhave been shown to make microplastics more harmful to Tetraselmis chuii at concentrations as low as a few parts per million (ppm). 133Studies found that PS complexed with roxithromycin exacerbated the effects of oxidative stress in red tilapia (Oreochromis niloticus) and Daphnia magna. 132Similarly, in Misgurnus anguillicaudatus, venlafaxine complexed with PVC-MPs boosted superoxide dismutase activity. 140Sulfamethazine, a different medication, also had a detrimental effect on the marine medaka (Oryzias melastigma) antioxidant system when it cooccurred with PSNPs. 130In a similar way, amplied lipid peroxidase activity was observed due to exposure to MNPs coronated with sertraline in Tegillarca granosa, 131 orfenicol in Corbicula uminea, 141 and cefalexin in Pomatoschistus microps. 142er entering and accumulating in these aquatic organisms, MNPs and co-pollutants enter the food web, as they are consumed by humans. 143

Potential impact of MNPs and copollutants on human health
MNPs are predicted to enter the body mostly through ingestion, inhalation, and skin contact 144 (Table 1 and Fig. 1).Concern over human exposure to these particles has been raised by recent discoveries of MPs in seafood, 28 entering through the food chain, and in drinking water (with food and air as additional sources of exposure). 9The inside lining of single-use paper cups was discovered to leach MNPs into hot water and hot beverages.In general, HDPE and co-polymers are used to generate these hydrophobic plastic liners, which constitute 5-10% of the total weight.Hot water exposure releases microplastics, toxic heavy metals such as lead, chromium, and cadmium, and ions including uoride, chloride, sulfate, and nitrate, 145 resulting in an average CDI (chronic daily intake) by humans of 0.03 ± 0.025 mg of microplastic per kilogram of body weight per day and 7.04 ± 8.8 g uoride per kilogram of body weight per day. 145,146o forecast the potential detrimental effects of MNPs on human health, researchers are continuing to use mammalian animal models.In the same vein, various in vivo and ex vivo investigations have shown the toxicity of MNPs in living cells. 155he cytotoxic effect of MNPs has been conrmed on numerous cell lines, for example, lung cells, 32 intestinal cells, 156,157 and many others.Cationic polystyrene nanoplastics (60 nm) were proven to affect cell viability and enhance inammatory gene expression in gastric cell lines, 158 macrophage 159 cell lines, and epithelial cells. 160The bioavailability of polystyrene MNPs in rat mammalian models was shown to be about 4% in the blood, bone marrow, liver, and spleen. 161Mice treated with PSMPs for 28 days exhibited the presence of PSMPs in the liver, kidney, and stomach. 162In a different study, mice exposed to PS showed signicant changes in the diversity and abundance of intestinal biota, as well as a decrease in intestinal mucus. 163,164Aer receiving 1 to 10 mg of PS NPs per kg of body weight per day for ve weeks, adult male Wistar rats displayed decreased locomotor activity. 165n addition to the toxicity of pristine MNPs to organisms, studies have also proven the toxic impacts of complexes of MNPs coronated with co-pollutants; however, only a few such studies exist.According to a recent study, the entry of environmental pollutants such as polychlorinated biphenyls (PCBs) into the body can disrupt and change the natural balance of a mother's milk, which can have negative health effects on nursing infants, including allergies and endocrine disorders, as well as impaired neurodevelopment. 166In previous investigations, it was discovered that sh experience endocrine disruption when the emerging pollutant metformin hydrochloride is released widely into wastewater treatment facilities. 167Functionalized PSNPs (pristine, carboxy, and amine), when combined with arsenic and methylmercury, altered transcription of oxidative stress genes and induced apoptosis in a brain-derived cell line (SaB-1) of seabream sh (Sparus aurata). 136The heavy metal arsenic, when complexed with PSNPs, induced apoptosis, pyroptosis, and excessive autophagy in the mouse liver. 37Compared to those exposed to pristine particles, mice exposed to MNPs and organophosphorus ame retardants simultaneously experienced higher levels of oxidative stress, neurotoxicity, and metabolic disturbance. 168Synthetic pollutants such as phthalates and bisphenols are found in many plastic products, including food containers, personal care items, and healthcare items.For example, phthalates, which may make up to 50% of the total mass of plastics, are additives that are frequently found in nanoplastics. 169They have the  ability to modify the endocrine system and are hence termed endocrine-disrupting compounds, which can subsequently lead to the development of breast cancer. 170These additives frequently include known carcinogens such as dioxins, polycyclic aromatic hydrocarbons, halogenated ame retardants, and heavy metals, and may be released from the polymers. 171he inherent properties of MNPs, the leaching of additives, and the release of persistent sorbed pollutants combine to cause the adverse effects of MNPs on the environment and living beings. 61n accordance with the outcomes of these experiments, it is believable to anticipate that MNPs and co-pollutants may have an impact on human health. 172

Interaction with the circulatory system
The toxicological effects of MNPs have been well investigated, but research on how these particles affect blood components leaves much to be explored.MNPs (particularly <1 mm MNPs) may pass through barrier cells such as bronchial epithelial cells and endothelial cells and enter the circulatory system. 173They have demonstrated their ability to translocate through the intestinal barrier and impact lymphocyte cells in in vitro models of the intestinal barriers. 30A hematological investigation on mice demonstrated that PSNPs with a size of 5 mm are transported by the bloodstream to the stomach, intestines, liver, and other digestive organs, as well as the bones of the animals. 174In mammalian animal models, it has been demonstrated that plastic particles 100 nm and smaller translocate via the pulmonary and gastrointestinal routes of exposure into tissues and the circulatory system. 175This leads to a presumption that aer internalization, the MNPs can interact with blood cell components and the vascular endothelium, which might lead to reactions such as MNP-blood interactions, cell damage, acute inammation, and chronic inammation. 56Therefore, hematopoietic cells, red cells, white cells, platelets, complement proteins, and plasma proteins have been hypothesized to be targets of MNP exposure.
However, if MNPs enter via an intravenous channel, the constituent parts of blood will come into contact with them rst.This interaction may result in a number of linked pathophysiological events, such as oxidative stress, genotoxicity, and cytotoxicity. 176The term "cytotoxicity" describes the capacity of a substance to harm or destroy cells.Genotoxicity is the term used to describe the capacity of a substance to harm DNA, resulting in mutations and other genetic alterations. 1779][180] Understanding how nanoparticles interact with blood components is a crucial rst step in evaluating their true hazard potential.
This paper aims to review the existing literature on the toxicity of micronanoplastics on blood components (Fig. 2).

Effect on plasma proteins
The liquid portion of blood, or plasma, is made up of several proteins, such as albumin, globulin, and brinogen.These proteins are essential for maintaining the osmotic balance of blood, carrying nutrients, and producing blood clots. 181lthough our knowledge of the effects of MNP exposure on many human cells (such as cell viability, chromosomal damage, toxicity, etc.) is constantly growing, there is relatively little data on the hazard potential of MNPs on human proteins. 57Hence, it is high time to focus on studies of the impact of MNPs on proteins.Fundamental bio-macromolecules called proteins are essential for cellular and organismal processes.Upon entry into the physiological context, MNPs bind with proteins immediately.Ligand-protein binding is the key factor in dening the toxicokinetics of any hazardous substance.When a chemical is consumed by an organism, its toxicokinetics are described through the measurement of its ADME: absorption, distribution (in the broadest sense), metabolism, and excretion.Toxicokinetics is a branch of toxicology that studies the destiny of a chemical in the body to calculate the amount of the poisonous substance (either parent molecule or metabolite) that reaches the portion of the body where it will exhibit its toxic impact within a given timeframe. 182Toxicokinetics information aids in better estimating health risks and can also aid in lowering the number of tests required to determine the hazardous effects of a chemical.The risk assessment methods for harmful compounds, such as toxicity testing, dose selection, and hazard assessment by comparing experimental animal versus human systemic exposure, might benet from a base set of necessary kinetic data. 183These chemicals are absorbed into the human body internally via ingestion, inhalation, and dermal exposure.Aer absorption, inhaled substances enter the lungs, from where they enter the bloodstream directly and travel to the heart, which is the next organ aer the lungs.Ingested substances entering the gut also arrive in the bloodstream and reach the liver as the rst organ. 182he second phase in toxicokinetics, i.e., the distribution of a substance and its metabolites inside the body, is inuenced by three major factors, namely, (1) The affinity of the substance for plasma proteins, (2) The partitioning between blood and specic tissues and, (3) The capacity of the substance to pass through biological membranes (e.g.: the blood-brain barrier (BBB) and the bloodplacental barrier (BPB)). 184he main element among these that affects the bioavailability and distribution of hazardous substances is plasma protein binding.A toxicokinetic investigation can rule out systemic toxicity if the plasma proteins do not bind to the MNPs.The systemic toxic effects can be anticipated to be minor if the binding is poor and the impacts on protein structure are extremely small; hence, toxicokinetics investigations can exclude systemic toxicity studies and suggest focus on other organ toxicity studies instead.However, strong protein binding prevents high-molecular-weight protein-ligand complexes from crossing biological membranes, resulting in impaired metabolism and renal clearance, which may be a sign of persistence and/or bioaccumulation. 49Interactions that are physical or chemical between these plastics and proteins (particularly plasma proteins) are the basis for the negative impacts of MNPs on human cells.MNP-protein complexes have an impact on the subsequent biological reaction.Hence, studies of the particular interactions between MNPs and various proteins must be investigated further in order to provide a foundational study that aids in the toxicokinetics and toxicodynamic proles of these hazardous chemicals.Recent research has demonstrated that once MNPs enter the bloodstream, they form a protein coating known as a "protein corona", which modies the physicochemical characteristics of the MNPs, such as their size, surface charge, and hydrophobicity, and also determines their fate in the body, including circulation time, distribution, uptake and internalization in cells, and toxicity. 185,186The formation of "hard" or "so" coronae is yet another topic under investigation in this regard.The term "so corona" refers to the creation of layers of extremely complex biomolecules that interchange quickly, whereas "hard corona" refers to a long life and low complexity balance. 187,188here are well-accepted in vitro methods to measure protein binding. 189,190These methods include mass spectrometry (to pinpoint the precise plasma proteins and associated amino acid residues that interact with ligand); 191 spectroscopic methods including UV-vis, uorescence, and circular dichroism spectroscopy (to investigate the modications in protein structure 192 brought on by the interaction with the ligand); electron microscopy (to visualize how MNPs interact with plasma proteins); 193 size-exclusion chromatography and highperformance liquid chromatography to separate proteins from ligands and analyze their binding. 194However, in the last two decades, uorescence spectroscopy and its calculations to measure protein binding have revolutionized these research areas.Weak, moderate, or strong protein-ligand binding can be found from the Stern-Volmer constants, quenching constants, binding constants, and thermodynamic constants, which are calculated from the results of the uorescence emission and excitation proles of a particular binding protein. 195,196luorescence spectroscopy, resonance scattering spectroscopy, UV-visible (UV-vis) absorption spectroscopy, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy were used to investigate the impact of polyvinyl chloride microplastics (PVC MPs) on bovine serum albumin (BSA) and human serum albumin (HSA) under simulated physiological conditions.PVC MPs alter the microenvironment and secondary structure (decrease in a-helix) of both proteins via electrostatic interaction. 197,198Interaction analysis of functionalized polystyrene nanoplastics (unfunctionalized: PS, carboxy: PS-COOH, and amine: PS-NH 2 ) with human hemoglobin (Hb) applying multi-spectroscopic and docking methods revealed that all the NPs bind with the hydrophobic pocket of the b-chain in Hb; PS and PS-NH 2 interact via hydrophobic forces, while PS-COOH binds via hydrogen bonding (predominantly) and van der Waals force, as validated from docking results.PS-NH 2 binds effectively and changes the conformation of Hb by increasing the hydrophobicity around aromatic residues, particularly tryptophan. 199A similar investigation using human brinogen (HF) revealed that nanoplastics disturb the structure of HF in a concentration-dependent manner, with PS-NH 2 having the greatest effect. 200Fluorescence correlation spectroscopy was used to assess the amount of transferrin adhered to sulfonate (PSOSO 3 H) and carboxyl-(PSCOOH) polystyrene NPs.The secondary layer (so corona) exhibits dynamic exchange since it is reversibly bound, but the rst layer (hard corona) is irreversibly bound.This suggests that an exposure memory effect may exist in the NP corona. 201This binding strategy at the molecular level should be explored for many more proteins so that a clear database of the distribution of NPs by proteins in the human body can be visualized and utilized for toxicokinetics studies. 202

Effect on hematopoietic cells
Hematopoietic stem cells (HSCs) are multipotent progenitors (common ancestors) that can regenerate all of the various cell types that make up the blood-forming system, and are capable of self-renewal. 203Since they are the base cell of the entire immune and blood systems, they are extremely sensitive to hazardous substances. 204Both bone marrow and peripheral blood contain HSCs, which can be differentiated into all of the adult functional blood cells, in lines known as myeloid and lymphoid cells.Myeloid cells include neutrophils, macrophages, basophils, eosinophils, monocytes, erythrocytes, and megakaryocytes to platelets.Lymphoid cells include T cells, B cells, natural killer cells, and innate lymphoid cells.Dendritic cell development involves both lymphoid and myeloid lineages. 205Studies have veried that exposure to MPs and NPs can impair mammalian hematopoiesis.Three different types of human hematopoietic cells-Raji-B (as a model for Blymphocytes), THP-1 (as a model for macrophages), and TK6 (as a model for lymphoblastoid cells)-have been used to examine the impact of polystyrene nanoplastics.Examination using TEM, confocal microscopy, and ow cytometry revealed that B-lymphocyte cells internalize PSNPs more than the other two models, and that the internalization is dependent on both particle size and cell type.Additionally, PSNPs promote cytotoxicity and cell stress by producing free radical ROS (reactive oxygen species) in blood cell lines.In Raji-B and THP-1 cells, PSNPs also caused the loss of mitochondrial membrane potential (MMP). 206Even at lower concentrations of 0.2 mg mL −1 , 80 nm PSNPs cause haematotoxicity in human CD34+ HSCs via cell internalization, elevated ROS, and lactate dehydrogenase (LDH) production, which results in cell death.Additionally, exposure to PSNPs alters the concentrations of metabolites such as amino acids, short-chain fatty acids (SCFAs), organic acids, fatty acids, and carbohydrates, primarily impacting the citrate cycle (TCA cycle) metabolism pathway in HSPCs.PSNPs strongly upregulated eight metabolites (dimethylglycine, propionic acid, oxoglutaric acid, nonanoic acid, linoelaidic acid, 2,2-dimethyl adipic acid, and glucose 6-phosphate) and considerably downregulated two metabolites (ethylmethylacetic acid, isocaproic acid). 207Colony-forming assay demonstrated that 5 mm of PSNPs could impact peripheral blood cell count by preventing the differentiation of bone marrow HSCs into granulocytes and megakaryocytes.Transcriptome analysis of mouse BM cells using RNA-sequencing technology revealed that genes involved in T cell homeostasis, osmotic stress response, extracellular matrix, and structural organization were altered, and metabolic pathways such as Jak/ Stat, fatty acids, and the pentose phosphate pathway NADP and nucleotide metabolism were all impacted. 174Aer differentiation and maturation in the thymus, T cells are distributed throughout the immunological organs via lymphatic and blood circulation to conduct immune activities.T cell homeostasis disruption will have an effect on the adaptive immune system, since it regulates lymphocyte development. 208Dysregulation of Jak/STAT signaling in humans will result in a variety of blood cell diseases and malignancies (leukemia). 209Multi-omics analysis using 16S rRNA, metabolomics, and cytokine chips to investigate potential hematopoietic system mechanisms in C57BL/6J mice demonstrated that intragastric administration of PSMPs and PSNPs with sizes of 10 nm, 5 nm, and 80 nm at a dose of 60 g for 42 days caused changes in gut microbiota, metabolites, and cytokines, which affected the proliferation and differentiation of HSCs. 210hus, exposure to MNPs impaired the ability of HSCs to selfrenew, proliferate, and differentiate indenitely, which led to disorders of the hematopoietic system.These results are useful in assessing the toxicity pathways and metabolite indicators of hematopoietic cell damage due to nanoplastic exposure, which can set the groundwork for early toxicity assessment and prevention.

Effect on red blood cells
Erythrocytes, which oen known as red blood cells (RBC), are the part of blood that actually carries nutrients and gases throughout the body.The adult erythrocyte is anucleate and has a biconcave discoid form.Their conguration enables them to move through the circulatory system and provide adequate gas exchange.The lifespan of a red blood cell is approximately 120 days.It must perform the necessary purpose in that brief period of time.RBCs are subjected to attacks throughout their lifespan, which cause continual morphological and physiological alterations. 51Changes in RBC morphology or a reduction in their lifespan will have health effects, and their assessment can reveal details about the general well-being of a person.Research points to oxidative stress and inammation of erythrocytes in chronic inammatory disease. 211Furthermore, the presence of nucleated red blood cells in circulation may be a sign of hemorrhage, hypoxia, hemolysis, and the presence of leukemia or other malignancies. 212The hemolytic potential of nanomaterials is well acknowledged, 211,213,214 and since prolonged hemolysis can have deadly health consequences, it is crucial to evaluate the hemolytic potential of each nanomaterial.Research on the effects of MNPs on red blood cells is still in its early stages; thus, additional studies are required to properly understand their effects.However, various studies have implied that RBCs may be adversely affected by microplastics.Polystyrene microplastics can signicantly enhance the generation of ROS, cause oxidative stress in RBCs and impact their overall functions.The RBCs of mice developed polycythemia in response to PSMPs, accompanied by a reduction in membrane elements, an alteration in bilayer thickness, and an increase in intrinsic lipid curvature.These ndings indicated RBC membrane function impairment. 215In a different in vivo experiment employing the C57BL/6 mouse model, animals were given daily 6, 60, or 600 mg per day doses of polyethylene microplastics for 15 days.The outcomes showed that the typical structure of their RBCs was signicantly altered by exposure to 600 mg per day of MPs, leading to a variety of aberrant forms. 216hen Nile tilapia (Oreochromis niloticus) were exposed to MPs, they experienced a huge increase in eryptosis (apoptosis), poikilocytosis (shape aberrations), and nuclear anomalies of RBCs. 217Among various surface functionalized PSNPs (pristine, COOH, and NH 2 ), amine-modied PSNPs with a size of 100 nm induced greater hemolysis with structural changes in human RBCs (since cell mediators, such as ATP, calcium, and GSH, were disturbed by the PSNPs), phosphatidylserine externalization, microvesicle generation and distress in the intracellular microenvironment.Similar results were observed in rat RBCs, showing no inter-species differences. 60Plastic additives can seep into the environment or food matrices and enter the human body.As an example, phthalates enter the body by ingestion, are absorbed into the bloodstream, and produce several abnormalities in erythrocytes, such as eryptosis, hemolysis, membrane aberrations, etc. 218 In addition to the toxicity of pristine MNPs, the impact of co-pollutants should be considered.One study reported that cadmium and PSMPs induced disruption of the membrane components and lipid bilayer of RBCs. 219[222] 7.4.Effect on white blood cells White blood cells (WBCs), which are oen referred to as leukocytes, are generated in the bone marrow and enter the bloodstream to serve a critical protective function in defense against infections, foreign objects, and aberrant cells.White blood cells include monocytes (differentiate into macrophages and dendritic cells: carry out phagocytosis), lymphocytes (B and T cells: control immune response), neutrophils (rst line of defense against infections), eosinophils (release enzymes that harm infected cells), and basophils (involved in defense mechanisms by presenting histamine and other chemicals and promoting inammation).The health of a person can be inferred from the quantity and distribution of these cells.Medical problems might be indicated by an aberrant WBC count, either excessively high (leukocytosis) or excessively low (leukopenia). 53Studies have demonstrated that WBC count and function may be negatively impacted by exposure to micronanoplastics.The cell counts in ve-week-old male C57BL/6 mice treated with 0.5 mg of 5 mm PSMPs were dramatically lowered according to toxicological tests. 174This reduced WBC count may be associated with the immunosuppressive effects of MNPs.In an ex vivo investigation, whole human blood samples were subjected to PSNP exposure, and it was discovered that PSNPs were internalized by monocytes and peripheral mononuclear cells (PMN), causing DNA damage and modications in the whole blood secretome.The expression of several cytokines related to inammatory, immunological, and stress responses, as well as cell proliferation, supported these ndings. 178MNPs can thus cause cellular cytotoxicity, oxidative stress, and white blood cell growth/reduction, which implies that MNPs can elicit an immunological response and potentially impair WBC function.In a study on human peripheral lymphocytes, 250 and 500 mg mL −1 concentrations of 10-45 mm red uorescent PEMPs markedly increased nucleoplasmic bridge formation (NPB), micronucleation (MN), and nuclear bud development (NBUD), which indicated genomic instability in lymphocytes. 46WBCs such as neutrophils and macrophages, which are referred to as phagocytes, can engulf, form phagosomes around, and "digest" antigens.The information from the antigens is then transmitted to the surface of the scavenger cells, where it is recognized by the adaptive immune system. 223When sh consume MNPs in an aquatic setting, there is evidence of cytotoxicity via enhanced neutrophil primary granule degranulation. 224When transgenic zebrash (Danio rerio) larvae Tg(lyz:DsRed2) were exposed to PS-MNPs and the co-pollutant cadmium, their neutrophil expression was altered, particularly in the case of nanoplastics +cd, which induced high immune toxicity by generating higher ROS levels in the larvae. 225An in vivo study using C57BL/6 mice showed that PSNPs induce inltration of macrophages, eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage uid with further induction of cytokine generation followed by lung inammation. 226Using rat basophilic leukemia (RBL-2H3) cells, it was discovered that PSNPs were internalized by basophils through interactions with cell membranes, endocytosis by clathrin-and caveolae-mediated pathways, and macropinocytosis.The PSNPs then became distributed in the cytoplasm and entered lysosomes before being released from cells through lysosome-mediated pathways and passive penetration. 227Similarly, 15 days aer the exposure of tilapia (Oreochromis niloticus) to MPs, a histological study of the kidney indicated loss of basophilic cytoplasm in a number of tubules, indicating cytotoxicity in basophils due to MPs. 228 In conjunction with the plasticizer di(2-ethyl)hexyl phthalate (DEHP), MPs signicantly elevated oxidative stress, increased the production of cytokines and neutrophil extracellular traps (Nets), and blocked the Wnt/b-catenin pathway, which resulted in inammation and skin brosis.Hence, co-pollutants mainly exhibit synergistic toxic injury with MNPs. 135In conclusion, research indicates that exposure to MNPs may detrimentally impact WBCs, including a decline in WBC count and interference with regular immune response processes.
In response to an inux of MNPs, WBCs and other immune cells such as natural killer cells, dendritic cells, and many others work together to release cytokines and other inammatory mediators that cause tissue damage, organ inltration, inammatory response, and ultimately systemic inammation. 229

Systemic inammation
Systemic inammation is caused by the endocytosis or phagocytosis of infectious bacteria, non-infectious agents such as exotoxic pollutants, and auto-immune molecules by immune cells.These agents trigger the release of immune system chemicals such as prostaglandins, cytokines, etc., leading to a cascade of reactions throughout the body, resulting in tissue damage and organ malfunction under chronic conditions. 230LRP3 inammasome is one such inammatory signal activated by the phago/endocytosis of exogenous pollutants and rupture and release of lysosomal contents such as reactive oxygen species (ROS) and many other mediators.This inammasome may be used as a sensor for detecting the immunotoxicity of MNPs. 231Polystyrene MNPs triggered ROS buildup and activation of the NLRP3 inammasome in human primary macrophages, 232 human monocytic (THP-1) 233 and mouse lung (MLE-12) cell lines, 234 and in mouse hepatocytes (AML12 cell line). 36Polystyrene MNPs have been proven to activate the NLRP3/caspase-1 signaling pathway in rat 235 and mouse 236 models in vivo, triggering inammatory reactions and pyroptosis.The presence of co-contaminants (arsenic) with PSNPs induced the above pathway leading to pyroptosis in the mouse liver. 37NPs cause higher inammation than MPs, as shown in one study in which NPs drove gut macrophage reprogramming and interleukin-1 (IL-1) production by inicting lysosomal degradation.This IL-1 signaling from the intestine can inuence brain immunity, resulting in Th17 differentiation and microglial activation, all of which are associated with a loss in cognitive function and short-term memory in mice. 40Female Sprague-Dawley rats that had inhaled polyamide MNPs showed elevated levels of proinammatory cytokines such as IL-6, CRP, and MCP-1 (biomarkers of systemic inammation) in their plasma 24 hours aer the inhalation. 237More research into the systemic inammation generated by MNPs is needed to determine the time course of this exposure and the inammatory cytokines.When earthworms were exposed to palladium-doped polystyrene nanoparticles, accumulation of the NPs and a decreased development rate (21.3-50.8%),decreased antioxidant enzyme activity, and an increase in ROS were observed.By internalizing these NPs (about 0.12 mg per cell), earthworm immune cells caused lysosomes to rupture, which then triggered autophagy and ultimately led to cell death. 238Using RAW264.7 cell macrophages, 4 mg mL −1 of 191.6 nm polyethylene terephthalate (PET), 1.85 nm PET, and low-density polyethylene (LDPE), which were produced as real-world plastics 239 from food containers and bottles, were examined for cell internalization.Macrophages serve as the rst line of defense against any foreign agents, and thus, the MNPs were taken up by the macrophages within 3 hours of incubation.The lysosomal activity was dramatically reduced by nano-PET particles; chronic modication of lysosomal activity and cellular homeostasis results in tissue degeneration and cellular damage. 159ALT1 expression was elevated in mouse lung tissue following co-exposure to HDM (house dust mites) and MNPs.Histamineinduced endothelial permeability and IgE-dependent mast cell cytokine production are mediated by MALT1, which is expressed in lymphoid, mast, and endothelial cells.This implies that co-exposure to allergens and MNPs may have a synergistically effect to intensify inammatory conditions. 326.Effect on platelets Blood cells known as platelets or thrombocytes are produced from megakaryocytes and exist in circulation for 5-7 days.They play a role in stopping bleeding from injuries, which starts with platelet activation (shape change) and adhesion to the vessel wall below the endothelium, and the release of chemical signals that cause platelet aggregation.The coagulation cascade is subsequently triggered, resulting in the transformation of brinogen into brin, which creates a mesh-like structure to support the clot.The blood clot shrinks, bringing the frayed edges of the blood vessel together and closing the wound.Once the wound has healed, the clot must be broken up in order to allow normal blood ow.This procedure, known as brinolysis, entails the activation of enzymes that disassemble the brin meshwork.54 Proper platelet activity is critical for overall health.Abnormalities of the platelets cause either excessive clotting or excessive bleeding.Platelet-related disorders include hemophilia, von Willebrand disease, and thrombocytopenia (low platelet count).55 Researchers have reported the interaction of platelets with nanoparticles as they circulate in the blood, which induces a chain of chemical signals leading to brin and clot formation (thrombi) and the development of cardio-or cerebrovascular blockages.240 Hence, it is critical to understand the thrombogenic capacity of any external agents entering the body.In a previous study by Kim et al. in 2022, in addition to affecting RBCs, PSNPs also had an impact on platelets in humans, modulating the coagulation cascade, RBC adhesion, and thrombus generation.Administration of PSNPs in rats also proved to induce thrombus formation.60 First, 100 nm PSNPs and PS-NH 2 were preincubated with either thrombin or brinogen in an ex vivo human thrombin/brinogen clot model, and brin clot formation was assessed using turbidity and thromboelastography (TEG).Microplastics have an inhibiting inuence on the production of brin clots.When rst incubated with thrombin, PS-NH 2 signicantly impacted clot strength and the rate of brin production; however, this impact was signicantly lessened when they were preincubated with brinogen.241 In another study using a microuidic-based in vitro thrombosis model, optical irradiation conrmed the tissue-injury-induced thrombosis following MNP exposure.242 When zebrash were exposed to copper co-pollutants combined with PSMPs, they increased the expression of genes encoding platelets (f5, ahsg2, serpina1, tor4aa, aldoaa, igf2b, hgfa, serping1, tfa, etc.), which might activate large numbers of platelets, and caused aggregation, coagulation, and clot formation.243 In a real-time analysis, thrombi were collected from patients who underwent cardiac surgery and analyzed using Raman spectroscopy.Surprisingly, the spectral data revealed the presence of exogenous microplastics in human thrombi, which conrms the clot formation ability of MNPs in the bloodstream.244 7.7.Effect on vascular endothelial cells Blood cells and proteins are frequently the main subjects of research in nanomaterial-blood interactions.However, it is also important to take into account the vascular endothelium in which these components are located.The endothelium is a thin layer of vascular endothelial cells that lines the inside of blood vessels.These cells are essential for maintaining blood vessel health and perform a variety of vital cardiovascular functions, including transporting nutrients and wastes across walls, regulating blood pressure, managing clotting and anticoagulation, controlling inammation, and secreting hormones and enzymes for vessel function/coagulation/inammation/ maintaining vascular homeostasis, assisting in angiogenesis, and performing vasodilation and vasoconstriction using nitric oxide and endothelin.245 Vascular endothelial dysfunction, which is caused by high blood pressure or inammation, contributes to a prothrombotic state and cardiovascular illnesses such as atherosclerosis/hypertension.246 Endothelial function is critical for overall cardiovascular health, and researchers continue to strive to comprehend the intricate relationships between endothelial cells and MNPs and their impact on health.The toxicological effects of inhaling polyamide MNPs (5 ± 1 mm) were evaluated in female 8-10 week-old Sprague-Dawley rats.The uterine vascular endothelial cells were affected, resulting in impaired vasodilation in microcirculation and elevated blood pressure. In vitro studies conducted on human cerebral microvascular endothelial cells (hCMEC/D3) showed that PS-NPs could enter the cells and trigger ROS generation, activate nuclear factor kappa-B (NF-kB), promote the synthesis of tumor necrosis factor (TNF-a), and cause necroptosis.This leads to a disruption of the tight junction of vascular cells, as seen from the decrease in transendothelial electrical resistance and reduced expression of occludin, which allowed for BBB passage and accumulation in the brain.39 In a recent study, researchers identied MNPs in fecal samples of patients with vascular calcication (VC).248 This is one of the pathological conditions in cardiac patients with the deposition of minerals in the vascular system, especially in the heart valves.249 Yan et al. reported in 2023 that PP-MPs and PSMPs were found in the feces of VC patients, and these particles induced mild VC in normal rats and intensied VC in vitamin D3 + nicotine-treated rats.Thus, MNPs in the vascular system can aggravate other pathological diseases in humans.248

Effect on complement proteins
The complement system is a collection of proteins that circulate throughout the blood and aid the ability immune system to ght illness by recognizing pathogens for phagocyte eradication.The native components are numbered C1, C4, C2, C3, C5, C6, C7, C8, and C9.C3 convertases are produced by complement activation, which cleaves C3 into C3b and C3a.Pathogens are marked for phagocytosis by C3b, which functions as an opsonin.Local inammatory reactions are triggered by C3a, C4a, and C5a, which draw immune cells to the infection site.A membrane-attack complex made up of the terminal complement proteins assembles to create membrane holes.Increased vulnerability to infection or severe tissue damage results from deciencies in the complement system or abnormal, unchecked complement activation. 250In freshwater benthic clams (Corbicula uminea), PSMPs were reported to trigger the innate immune response by activating the complement and coagulation cascade pathways.In response to MPs, differentially expressed genes were noticeably enriched in these pathways.The major genes of the complement cascade system (TIRINITY _ DN4384_ c0_ g1, TIRINITY _ DN4871_ c0 _ g1, TIRINITY _ DN1178 _ c0 _ g1, TIRINITY _ DN3052 _ c0 _ g4, TIRINITY _ DN14985 _ c0 _ g1, and TIRINITY _ DN20036 _ c0 _ g1) were considerably elevated in the presence of MPs according to RT-qPCR results.Complement factor B (CFB), a part of the alternate pathway of the complement system, was also markedly increased.Additionally, the increased aggregation of pathogenic bacteria and the elicitation of hub genera demonstrated intestinal inammation, supporting the MP activation of the complement and coagulation cascade pathways. 47In adult zebrash (Danio rerio), exposure to PEMPs for seven days caused changes in the gut microbiome that increased the likelihood of infection in the intestinal mucosa.A dose-dependent increase in complement C3 and C4 content was observed when MPs activated the intestinal immune network pathway for the generation of mucosal immunoglobulins.The relative abundance of the Plesiomonas genus was favorably linked with the expression of immune-related genes (pigr, il10, and ighv4-5). 251Microplastic exposure can impair immune function by suppressing the apoptosis-related molecular pathways and calcium signaling of the complement system, among other immune-systemdisrupting effects. 252These ndings imply that microplastics affect the complement system and the capacity of the body to ght off foreign substances.

Effect on biochemical parameters
Biochemical parameters, which are chemical substances found in the blood, are indicators of health (including autoimmune illnesses, inammatory conditions, and more) and organ health (such as the liver, kidneys, etc.).These include bilirubin, blood urea nitrogen, uric acid, creatinine, cholesterol, C-reactive protein (CRP), alanine transaminase (ALT), alkaline phosphatase (ALP), aspartate transaminase (AST), lactose dehydrogenase (LDH), and many others. 253Microplastics have been proven to alter hemato-biochemical parameters and produce anemia. 254An early juvenile Nile tilapia (Oreochromis niloticus) sh showed a signicant increase in biochemical markers (creatinine, ALP, AST, ALT, glucose, uric acid, cholesterol, and total protein) aer being exposed to microplastics for 15 days. 255pon exposure to 500 and 1000 mg kg −1 MPs, the European pond turtle (Emys orbicularis) showed an increase in ALT, ALP, AST, creatinine phosphokinase (CPK), cholesterol, glucose, creatinine, urea, and calcium (Ca 2+ ) activity and a decrease in LDH, triglyceride, total protein, albumin, total immunoglobulins, and phosphorus levels. 21Similarly, in common carp (C.carpio), following exposure to 0.4 mg L −1 of the herbicide paraquat and a combination of paraquat and microplastics, the AST, ALP, ALT, LDH, creatinine, CPK, glucose, and albumin levels increased, whereas the total protein, globulin, cholesterol, and triglyceride levels decreased, as well as the -glutamyl transferase activity.Based on these ndings, higher concentrations of microplastics in the water considerably exacerbated the hazardous effects of the co-pollutant paraquat on sh. 256As a result, modications in blood biochemical parameters may be a suitable biomarker to show the presence of tissue injury.
Among all the blood components discussed, plasma proteins, HSC, RBC, WBC, immune cells, platelets, and vascular endothelial cells are of particular interest.The impact on plasma proteins will lead to whole-body nutrient and oxygen deciency.Further, alterations to the structure of HSA may impact its esterase enzymatic activity. 257This would impair the ability of HSA to bind to ester-containing hazardous compounds, which could lead to a decrease in the natural detoxication ability of the human body. 258WBCs and immune cells are the basis for the immunity of an individual.The destruction of these cells can pave the way for numerous immune deciency diseases.Toxic impacts on RBCs, platelets, and ECs cells can lead to life-threatening cardiovascular and cerebral diseases.Hence, research should be conducted on these components to understand the extent of MNP toxicity and to take preventive measures.The severity of MNP toxicity can be evidenced by recent research in which microplastics (poly(methyl methacrylate)) were detected in the heart (le atrial appendage, epicardial adipose tissue, and pericardial adipose tissue) of cardiac surgery patients 259 and MPs were detected in thrombi isolated from cardiac patients. 244

Distribution to other organs and toxicity
Following their journey in the circulatory system, MNPs are dispersed throughout the organs, where they accumulate, disrupt metabolic pathways, elicit immunological responses, and, in more extreme cases, lead to immune dysfunction.Major organs like the lungs, liver, kidneys, and brain can be invaded by MNPs through blood circulation. 252Research on CD1 mice 260 and C57BL/6 J mice 160 has also proven that PS-MNPs were found to accumulate in the blood and other organs, i.e., the spleen, lung, kidneys, liver, small intestine, heart, etc. Toxicity in the lungs was reported by Nemmar et al. in 2003 in hamsters; amine-PSNPs (60 nm) penetrated the pulmonary blood barrier, leading to pulmonary thrombosis and inammation. 261A study conducted using PS-COOH with sizes of 40 and 200 nm to assess internalization by different organs indicated that the MNPs were taken up by HeLa (cervical cells), A549 (lung cells), and 1321N1 (brain cells) human cell lines. 262With a mean residence period of 17 days and a bioaccumulation factor (BCF) of ∼8, the gut had the highest level of exposure to 5 mm PSMPs. 263It was found that 0.1 mm PSNPs can enter hepatocytes from the bloodstream and cause DNA damage in the mitochondria and nucleus, which causes the dsDNA fragment to enter the cytoplasm and activate the DNA-detecting adaptor STING.The downstream cascade response was started by the activation of the cGAS/STING pathway.The NF-kB translocated into the nucleus and increased the release of pro-inammatory cytokines, ultimately accelerating liver brosis. 35Studies on shortterm absorption in mice using the oral administration of polystyrene MNPs (9.55 m, 1.14 m, 0.293 m) revealed that NPs enter the brain 2 hours aer gavage.Protein molecules hindered the uptake of these NPs into the blood-brain barrier, whereas cholesterol molecules promoted it. 264MNPs are transferred to the placenta and ltered into the fetal organs, according to studies.Hesler et al. (2019) used BeWo b30 cells and 50 and 500 nm carboxy-modied polystyrene particles in their study and found weak embryotoxicity and non-genotoxicity at the concentrations tested (0.1-10 g mL −1 ), and no negative effects of NP exposure on placental barrier integrity. 265An in vivo study proved that carboxylate-modied polystyrene particles of 20-500 nm were dispersed in the fetal brain, lungs, and liver aer crossing the mouse placenta. 42In 2020, using uorescent optical imaging and hyperspectral darkeld microscopy, Fournier et al. reported the distribution of 20 nm rhodamine-labeled polystyrene beads in fetal liver, kidney, lung, heart, and brain tissues aer intratracheal instillation of pregnant rats in late gestation.This nding suggests that NPs can migrate via the placenta and diminish fetal and placental weight, implying that exposure to plastic particles during pregnancy may have an impact on birth outcomes. 31In a recent sh study conducted in a realistic environment, MNP accumulation in the internal organs such as the gills (11.1 mm size of MNPs), heart (6.8 mm), kidneys (9.8 mm), and digestive system (25.9mm) was observed, and the MNPs in the heart were in the same size range as hematocytes, which strengthens the crucial role of the circulatory system in the distribution of MNPs. 266

Implications for human health
The toxic responses of various blood components to MNPs and co-pollutants (Table 2) were thoroughly addressed in the previous sections.It is critical to understand how these harmful responses will affect human health.Alterations in the conformations of plasma proteins due to MNPs affect their functions such as the transportation of nutrients, oxygen, minerals, drugs, etc., which might lead to nutrient deciency, oxygen deciency, iron deciency, drug inefficacy and many other effects.Cytotoxicity, genotoxicity, and the inability of HSC cells to differentiate and proliferate can result in impaired T-cell and B-cell hemostasis and hematopoietic disorders such as anemia, blood cancer, autoimmune diseases, etc.The hazardous effects on RBCs could result in hemolytic anemia, iron deciency anemia, RBC aggregation, and aberrant clots in the body.Cytotoxicity, oxidative stress, cell organelle failure, apoptosis of WBC and immune cells, and the up-or down-regulation of cytokines and other inammatory chemicals all contribute to immunological deciency, inammation in the blood and other organs, and systemic inammation.Platelet abnormalities

Key findings
The potential consequences of the entry of micronanoplastics (MNPs) into the bloodstream via intravenous channels or barrier cells have been covered in this article.The following are key ndings from the literature review.
(1) While circulating in the bloodstream, MNPs develop "hard" and "so" coronae with plasma proteins (HSA, hemoglobin, transferrin, brinogen, etc.), which inuence their structure and functionality.This will ultimately impact how nutrition, oxygen, medications, and many other substances are transferred throughout the body.For example, PSNPs alter the conformation of HSA 271 and hemoglobin. 199In the area of toxicokinetics studies, more investigation into MNP-protein interactions is necessary.
(2) HSCs (hematopoietic stem cells) are essential for the regeneration of all blood cells.MNPs cause HSC cytotoxicity in addition to suppressing HSC proliferation and differentiation, which might result in hematopoietic diseases.Haematotoxicity in human CD34+ HSCs resulted from cell internalization, elevated ROS, and lactate dehydrogenase (LDH) production by MNPs. 207Furthermore, modication of the metabolic pathway of HSCs was validated by transcriptome and multi-omics analyses.
(3) In RBCs, MNPs cause hemolysis as well as additional risks including oxidative stress, structural changes, and functional impairments, which can result in hemorrhage, hypoxia, malignancies (polycythemia), and many other conditions.PENPs were found to alter the RBC structure in a C57BL/6 mouse model. 2164) MNPs have the potential to negatively impact WBCs (monocytes, lymphocytes, neutrophils, eosinophils, and basophils), which could compromise the effectiveness of the immune system and raise concerns about general health.These negative impacts include DNA damage, alterations in cytokine expression, an increase in oxidative stress, changes in immunological response, disruptions in antigen processing function, and degranulation leading to inammation and stress response.WBC count was drastically reduced in C57BL/6 mice treated with 0.5 mg of 5 mm PSMPs, which supports the abovementioned effects.174 (5) MNPs have been discovered to be phagocytosed by immune cells, such as macrophages, as evidenced by an increase in the generation of proinammatory cytokines  231 etc.) and prostaglandins.As a result, signaling pathways change, oxidative stress increases, and lysosomes rupture, which further leads to autophagy, cytotoxicity, pyroptosis, and organ inammation, all of which can eventually result in systemic inammation, tissue damage, and organ malfunction.More research is needed, however, to determine the overall degree of MNP-induced inammation in the body.(6) The effects of MNPs on platelets have been demonstrated to affect the coagulation cascade as well as events including red blood cell adhesion and thrombus (blood clot) formation.Platelets are necessary for preventing excessive bleeding/ clotting and preserving overall health, but abnormal activity can result in coagulation disorders such as abnormal clotting or bleeding.For instance, carboxy PSNPs caused platelet aggregation via upregulation of adhesion receptors.273 (7) MNPs have been reported to decrease complement system pathways by modifying their genes and protein expression (for example, complement protein B increased in benthic clams due to PSNPs), 47 hence compromising their involvement in immune function.(8) The vascular endothelium, a crucial component of blood vessels, is essential for sustaining cardiovascular health and cerebral function.According to research, MNPs can impair vascular endothelial function by producing impaired vasodilation, elevated blood pressure, inammatory reactions, and coagulation issues, which can contribute to cardiovascular disorders such as atherosclerosis and hypertension.For example, PSNPs affect tight junctions of human cerebral microvascular endothelial cells, possibly damaging the BBB.39 (9) MNPs alter the levels of hemato-biochemical parameters such as bilirubin, blood urea nitrogen, uric acid, creatinine, LDH, triglycerides, albumin cholesterol, C-reactive protein (CRP), and liver enzymes (ALT, ALP, AST), which may lead to a multitude of health problems, including autoimmune diseases and inammation.Fish models presented signicant increases in biochemical markers (creatinine, ALP, AST, ALT, glucose, uric acid, cholesterol, and total protein) when exposed to MNPs for 15 days.228 Briey, this article has emphasized the possible toxicity of MNPs on blood components as well as the necessity for additional research in this eld.

Research gaps in toxicological information and future perspectives
Although substantial progress has been made in the eld of the toxicity of microplastics in blood, there are still many research gaps and areas that need to be further explored.They are as follows: (1) Realistic exposure: The most signicant research gap is the lack of toxicity data for real-world MNPs (true-to-life plastics).More research is required to mimic real-world exposure settings, including examining the root cause of MNP contamination in the bloodstream and any potential health effects.
(2) Combined toxicity of MNPs and co-pollutants: Despite scientic evidence showing the deleterious impact of MNPs on the circulatory system, studies on the combined impacts of MNPs and co-pollutants are extremely rare.To determine how these co-contaminants and microplastics might interact and whether their combined presence worsens toxicity, more research is required.
(3) Toxicity of monomers: Nanoplastics can be degraded further to monomers.Polystyrene, for example, is made up of styrene monomers that are bonded together.Since PS is widely used in food containers, PSNPs and styrene monomers may leach into food and enter the human body.It has been discovered that this monomer is more harmful to mucous membranes, the respiratory system, the neurological system, and the reproductive system.Furthermore, the WHO has designated styrene as a potential human carcinogen. 287Similarly, the hazardous effects of various plastic monomers on ecosystems and humans, particularly blood components, must be investigated.
(4) Advanced technologies to determine toxicity: Methodologies such as in silico analysis, machine-learning algorithms, and ADMET analysis will aid in the detailed assessment of the binding of MNPs and their toxicological prole in the human body.ADMET studies include experiments to determine the adsorption, distribution, metabolism, excretion, and toxicity of substances.For example, absorption through the blood-barrier barrier or GI tract can be predicted through the BOILED-Egg method. 2885) Human studies: To date, in vivo toxicity studies have been conducted using animal models, and the results have been extrapolated to human health implications.Consequently, toxicity studies utilizing human-relevant experimental models must be conducted.
(6) Bioaccumulation: MNPs can enter the bloodstream and be transported to many organs and tissues according to studies.However, it is necessary to examine how they accumulate in the blood and other organs.In this context, in addition to acute exposure studies, a research gap exists regarding the potential chronic effects of MNPs in circulation.This research gap must be lled in order to calculate the bioaccumulation factor.
(7) Inammatory pathways: Researchers are trying determine the pathways involved in the toxic effects of MNPs, for example, the JAK1/STAT3/TF and Wnt/b-catenin pathways.However, numerous pathways have yet to be identied, and further exploration is required.
(8) Immunological response: Regarding immune system toxicity, a basic understanding of how MNPs alter immunological responses, enhance oxidative stress, trigger inammation, and decrease immune cell function has been established, but further research is necessary to fully understand how these effects relate to clinical disorders.
(9) Dose-response relationships: It is critical to establish dose-response relationships to ascertain the concentrations of MNPs in the bloodstream that may have a negative impact on health.To determine their inuence, tests must be run with different MNP concentrations.
(10) Physiochemical characteristics of MNPs: MNPs with different characteristics, such as type, size, shape, and surface qualities, may have variable levels of toxicity.This aspect must be investigated in the bloodstream.(11) Difference in toxicity among people: Further, the impact of microplastics in the bloodstream should be studied to see whether any particular demographic is more susceptible, such as young people, the elderly, or people with prior medical issues.
It is imperative to address these research gaps to achieve a complete understanding of the toxicity of MNPs and their complexes in the bloodstream and their potential impact on human health.This will also provide direction for the establishment of efficient risk assessment and mitigation measures.

Conclusion and outlook
MNPs have become a major environmental concern, raising concerns about their possible inuence on the health of humans and other organisms.The hazardous effects of MNPs and their complexes with other pollutants on the aquatic and terrestrial environments have been proven in numerous studies.The negative impact of these particles on mammalian models and cell lines has been explicitly studied and the results are oen expanded to human health.The current paper critically reviews technical investigations on the impact of MNPs and their co-pollutant complexes on blood and blood components.The presence of MNPs in a dynamic environment such as the bloodstream may have potentially deleterious effects due to interactions with diverse blood components, which represents a new area of research with substantial implications for human health.They have the ability to adsorb plasma proteins and complement proteins, as well as to form protein coronae, which can impact their action in biological systems.MNPs have been shown in vitro to have cytotoxic, genotoxic, and oxidative stress effects on blood cells.The reported scientic investigations have revealed the harmful effects of MNPs related to blood disorders such as anemia, thrombosis, cardiac diseases, and nutrient and oxygen deciency, as well as immune system disorders.However, there are still many grey areas regarding the effects of MNP exposure in the bloodstream, due to the lack of studies on the combined toxicity of MNPs and copollutants, the effect of real-world MNPs, the effect of monomers and toxicological studies in humans, advanced methods to determine toxicity, bioaccumulation, inammation, immunological pathways, and the impact of different concentrations of toxicants and their physiochemical characteristics.In this regard, this article has aimed to shed more light on the research gaps to be addressed immediately to better understand the extent and implications of the interaction between MNPs and blood components, as well as to create effective measures to lessen their potential negative impacts on human and environmental health.

Fig. 1
Fig.1Routes of entry of micronanoplastics into the human body.

Fig. 2
Fig.2Interactions and negative effects of MNPs on blood components.

199 PSNPs 271 PSNPs
by hydrophobic interactions, promote amyloid bril formation, and change the protein structure.Amyloid brils form at the interface and junction of the NPs bind with B-chain in Hb, PS and PS-NH 2 -hydrophobic force PS-COOH -hydrogen bonding and van der Waals force.PS-NH 2 inuences the structure more.Disturbs functional structure, and might affect oxygen carrying capacity secondary structure, affects esterase-like enzyme activity, and might affect nutrient transfer capacity and THP-1 cells' uptake of PSNPs is greater.Loss of mitochondrial membrane potential -observed for Raji-Reduced CF unit-granulocyte-macrophage (CFU-GM), and CFU granulocyte, erythrocyte, monocyte, macrophage (CFU-GEMM).MNPs impacted the proliferation and differentiation of HSCs and hindered erythropoiesis

Table 1
Routes of entry of micronanoplastics into the human bodyRoute of entry Source of MNP contaminationRef.

Table 2
Different MNPs and their toxic effects on various blood components

Table 2 (
Contd. ), and persistent bleeding in the skin, gums, and other internal organs.The senescence or apoptosis of vascular endothelial cells along with RBC and platelet aggregation produces clots in blood vessels.These obstructions might cause cardiovascular disorders (e.g., atherosclerosis) and brain ailments (e.g., stroke).Alterations in the levels of biochemical parameters cause changes in overall body metabolism.Negative effects on complement proteins weaken immunity and increase the likelihood of infection.These implications to human health urge the necessity of further in vivo research and mitigation measures to control plastic pollution.